Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Oral Communication Abstract - S3c

TRITERPENOID SAPONINS FROM ASTER SEDIFOLIUS: CHEMICAL CHARACTERIZATION, ANTIFUNGAL ACTIVITY AND EXPRESSION OF 2,3-OXIDOSQUALENE CYCLASE GENE

M. CAMMARERI*, M. ZACCARDELLI**, G. COREA***, V. LANZOTTI****, A. ERRICO*, C. CONICELLA*****

*) Dept. of Soil, Plant and Environmental Sciences, University of Naples "Federico II", via Università 133, 80055 Portici-NA (Italy)

**) Research Institute for Industrial Crops - MiPAF - ss.18, n° 156, 84091 Battipaglia -SA (Italy)

***) Dept. of Natural Product Chemistry, University of Naples "Federico II", via D. Montesano 49-I, 80131 Napoli (Italy)

****) Dept. of Science and Technologies for Food, Environment and Microbiology, University of Molise, Via De Sanctis, 86100 Campobasso (Italy)

*****) CNR-IGV, Research Division Portici, via Università 133, 80055 Portici-NA (Italy)

triterpenoid saponins, Trichoderma viride, 2,3-oxidosqualene cyclase gene

Plants elaborate a vast array of natural products, which can be interesting for pharmaceuticals and biopesticides. The saponins are glycosides occuring in more than one hundred plant families and in some marine animals. In particular, triterpene saponins are isoprenoidal natural products with remarkable structural varieties as well as notable biological activities.

The triterpenes are biosynthesized from a common precursor: 2,3-oxidosqualene. The cyclization of 2,3-oxidosqualene into tetracyclic and pentacyclic carbon skeleton is catalyzed by enzymes termed 2,3-oxidosqualene cyclases (OSCs). They exhibit a highly similar amino acid sequences, such as QW and DCTAE motifs.

The material which has been utilized in the present work for gene cloning and new substances purification is coming from a germplasm collection of Aster spp. The research dealed with the following topics: 1. the chemical structure of triterpenoid saponins extracted from Aster sedifolius; 2. the analysis of their antifungal activity in plant; 3. the expression of 2,3-oxidosqualene cyclase gene involved in the biosynthetic pathway.

Three novel substances isolated from aerial parts of Aster sedifolius were characterized as triterpenoid saponins with oleane-type skeleton. Anti-tumoral effect of these substances is in progress. Biological tests with leaf extracts against Trichoderma viride and Botrytis cinerea evidence inhibition of fungal mycelium growth. Expression studies have been performed by RT-PCR with specific primers which amplify a fragment of 300 bp in 2,3-oxidosqualene cyclase gene of Aster sedifolius. The results evidence differential tissue expression between in leaf, flower and root.